Mortarless masonry wall systems are comprised of concrete masonry units laid dry and subsequently grouted, partially grouted, or suface bonded.  Applications of mortarless wall systems include basement walls, foundation walls, retaining walls, exterior above-grade walls, internal bearing walls and partitions.
 

The construction of masonry wall systems is possible without the use of mortar.  Comprised of fabricated Concrete Masonry Units (CMUs) often referred to as "dry-stack units" that are surface bonded with fiber cement, these structures are often included in the following system types:

                  -grouted, partially grouted or surface bonded
                  -unreinforced, reinforced, or pretressed

Specifically designed units for dry-stack construction are available in many different forms.  The most sophisticated designs incorporate face shell alignment features that make units easier and faster to stack plumb and level.  Other units are fabricated with a combination of keys, tabs or slots along both horizontal and vertical faces so they interlock easily.  Physical tolerances of dry-stack concrete units are limited to +/- 1/16 in. (1.58mm.) which precludes the need for mortaring, grinding of face shell surfaces or shimming to even out courses during construction.  Interlocking units placed in running bond resist flexural and shear stresses results from out-of-plane loads as a result of keying action.

The interlocking features of dry-stack units improve alignment and leveling, reduce the need for skilled labor and reduce construction time.  Floor and room systems can be supported by mortarless walls with a bond beam at the top of the wall which expedites the construction process.

Dry-stack concrete masonry units can be used to construct walls that are grouted or partially grouted; unreinforced, reinforced or prestressed; or surface bonded.

 

• Faster installation.  Mortarless concrete masonry units can be installed up to 10 times faster than conventional block, dramatically reducing labor costs.
• Easier installation.  Because dry-stacked, interlocking block self-aligns and self-seats, it can be laid by semi-skilled and unskilled workers, increasing the productivity of apprentices and laborers.
• All-weather construction.  Mortarless systems can be stacked in all weather conditions, speeding construction.

Care must be taken in evaluating risk reduction with substitute building systems, since many variables are involved.  For example, trowling of surface bonding agents,  or other tasks that are introduced may also introduce unrecognized strains or risks of injury.

A higher block laying rate may lead to increased arm, shoulder and back exhaustion.  Job rotation during a shift and more frequent, shorter breaks should be considered as means of preventing injury.